mirror of https://gitee.com/openkylin/linux.git
70 lines
2.0 KiB
Plaintext
70 lines
2.0 KiB
Plaintext
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Copyright (C) 2018 Intel Corporation
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Author: Sakari Ailus <sakari.ailus@linux.intel.com>
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Referencing hierarchical data nodes
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-----------------------------------
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ACPI in general allows referring to device objects in the tree only.
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Hierarchical data extension nodes may not be referred to directly, hence this
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document defines a scheme to implement such references.
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A reference consist of the device object name followed by one or more
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hierarchical data extension [1] keys. Specifically, the hierarchical data
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extension node which is referred to by the key shall lie directly under the
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parent object i.e. either the device object or another hierarchical data
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extension node.
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Example
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-------
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In the ASL snippet below, the "reference" _DSD property [2] contains a
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device object reference to DEV0 and under that device object, a
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hierarchical data extension key "node" referring to the NODE object and
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lastly, a hierarchical data extension key "anothernode" referring to the
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ANOD object which is also the final target of the reference.
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Device (DEV0)
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{
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Name (_DSD, Package () {
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ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
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Package () {
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Package () { "node", NODE },
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}
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})
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Name (NODE, Package() {
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ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
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Package () {
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Package () { "anothernode", ANOD },
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}
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})
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Name (ANOD, Package() {
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ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
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Package () {
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Package () { "random-property", 0 },
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}
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})
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}
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Device (DEV1)
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{
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Name (_DSD, Package () {
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ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
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Package () {
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Package () { "reference", ^DEV0, "node", "anothernode" },
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}
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})
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}
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References
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----------
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[1] Hierarchical Data Extension UUID For _DSD.
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<URL:http://www.uefi.org/sites/default/files/resources/_DSD-hierarchical-data-extension-UUID-v1.1.pdf>,
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referenced 2018-07-17.
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[2] Device Properties UUID For _DSD.
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<URL:http://www.uefi.org/sites/default/files/resources/_DSD-device-properties-UUID.pdf>,
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referenced 2016-10-04.
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